RFR: JDK-8211241: Missing obj equals in TemplateTable::fast_aldc

[Roman Kennke]

Included hotspot-runtime-dev because it's an interpreter bug, excluded
hotspot-compiler dev, and also here's all the links:

Bug:
https://bugs.openjdk.java.net/browse/JDK-8211241
Webrev:
http://cr.openjdk.java.net/~rkennke/JDK-8211241/webrev.00/

It's never been quite clear to me where to put interpreter bugs.
hotspot/runtime in Jira and hotspot-runtime-dev on mailing lists? Is
that right?

Thanks, Roman



> TemplateTable::fast_aldc compares the just-loaded reference with
> Universe::the_null_sentinel. If it really is that null-sentinel, we may
> get a false negative (with GCs like Shenandoah that allow both
> from-space and to-space copies of an object to be around), and thus skip
> NULL-ing the ref. In other words, it would allow to get
> the-null-sentinel out into the wild as oop which can cause subtle and
> not-so-subtle bugs.
> 
> Fix is easy, call cmpoop() which re-routes through GC-interface for GCs
> that need it:
> 
> http://cr.openjdk.java.net/~rkennke/JDK-8211241/webrev.00/
> 
> Testing: hotspot/jtreg:tier1
> 
> Ok?
> 
> Roman
>